Magnetic antenna having a block or circuit components therein

ABSTRACT

An antenna for a receiver comprising a magnetic core in the form of a thin layer having a thickness less than 50 microns superposed on a casing of a receiver or on a block of components of the receiver, and a winding wound on said magnetic core and connected electrically to the components in the casing or in the block, the winding serving as the antenna for the receiver. A receiver which comprises said antenna.

Related US. Application Data Continuation-in-part of Ser. No. 679,351,Oct. 31, 1967, abandoned.

Umted States Patent 1 111 3,778,836 Tanaka Dec. 11, 1973 [54] MAGNETICANTENNA'HAVING A BLOCK 3,271,718 9/1966 Shaw 336/234 x 3,372,395 3/1968Kline 0R CIRCUIT COMPONENTS THEREIN 3,538,441 11/1970 Tanaka 343 702 X[76] Inventor: Takashi Tanaka, 340 Oaza Kisaichi,

Katano-cho, Kitakawachi-gun, FOREIGN PATENTS OR APPLICATIONS Osaka-f,Japan 1,090,140 6/1958 Germany 343/787 [2 Filed: p 27, 1971 OTHERPUBLICATIONS [21] App]. No.: 137,998 Polydoroff, W. .1R.E.E.Ferromagnetic Loop Antennas, Radio-Electronic Eng. Edition ofRadio & TV News, 11-1951, pp. 11-13, 24.

Polydoroff, W. J High-Frequency Magnetic Materials John Wiley & Sons,1960, pp. 1-3.

Burgess, R. E., Iron-Cored Loop Receiving Aerial Wireless Engineer,6-1946, pp. 172-178.

Primary Examiner-Rudolph V. Rolinec Assistant ExaminerWm. H. PunterAtz0rneyWenderoth, Lind & Ponack 5 7 ABSTRACT An antenna for a receivercomprising a magnetic core in the form of a thin layer having athickness less than 50 microns superposed on a casing of a receiver oron a block of components of the receiver, and a winding wound on saidmagnetic core and connected electrically to the components in the casingor in the block, the winding serving as the antenna for the receiver. Areceiver which comprises said antenna.

10 Claims, 7 Drawing Figures MAGNETIC ANTENNA HAVING A BLOCK OR CIRCUITCOMPONENTS THEREIN This is a continuation-in-part of application Ser.No. 679,351, filed Oct. 31, 1967, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to an antenna for a receiver for electromagnetic waves such as aradio receiver, and more particularly to an antenna comprising amagnetic core in the form of a thin layer superposed on the casing ofthe receiver or on a block of components of the receiver.

2. Prior Art A conventional antenna for use in a receiver, such as aradio receiver, comprises a magnetic core having a winding thereon. Themagnetic core consists of, for example, a ferrite material having a highmagnetic permeability and is usually in the form of a rod, a plate, or atube. It is well-known that the ratio of the length to thecrosssectional area of a magnetic core is one of the factors whichaffects the sensitivity of an antenna having said magnetic core. Ahigher ratio results in a higher sensitivity. As a practical matter, itis not easy to obtain a higher ratio because the maximum length of themagnetic core is limited by the size of the casing containing the radioreceiver. It is also difficult to reduce the cross-sectional area of themagnetic core of a ferrite because the ferrite has poor mechanicalstrength. For example, a thin rod or plate which is long is easilybroken, if the receiver is dropped carelessly on the ground duringhandling. A tubular core has a higher mechanical strength than a rodcore with the same cross-sectional area and length, but the tubular corehas a larger outside dimension than a rod core.

It is desirable that a receiver be small in size. Recent developments inthe electronic component industry have succeeded in miniaturizing theelectronic components by employing various new elements, for example,transistors instead of electron tubes. Moreover, new techniques such asthose for making micromodules and integrated circuits have increased thepacking density of the components. On the other hand, it has not beenpossible to reduce the size of the antenna without decreasing thesensitivity and/or the mechanical strength thereof. Therefore, theconventional antenna occupies quite a large space in a radio receiver incomparison with the other miniaturized components and limitsminiaturization of a receiver.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide an antenna having a high sensitivity, a high mechanical strengthand/or a small volume.

Another object of the invention is to provide an antenna comprising amagnetic core in the form of a thin layer having a thickness less than50 microns superposed on the casing of a receiver or on a block ofcomponents of a receiver.

A further object of the invention is to provide a receiver, the casingof which has a magnetic core in the form of a thin layer superposedthereon which acts as an antenna.

A further object of the invention is to provide a receiver in which ablock of components are combined with a magnetic core in the form of athin layer superposed thereon.

The antenna according to the invention comprises a magnetic core in theform ofa thin layer superposed on a casing of a receiver or on a blockof components of a receiver and a winding on said magnetic core.

BRIEF DESCRIPTION OF THE FIGURES The invention will now be described inconnection with the accompanying drawings, in which:

FIG. 1 is a perspective view of one embodiment of an antenna accordingto the invention, partly broken away;

FIG. 2 is a longitudinal sectional view of the antenna of FIG. 1;

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2;

FIG. 4 is a perspective view, partly broken away, of

another embodiment;

FIG. 5 is a longitudinal sectional view of the antenna of FIG. 4;

FIG. 6 is a cross-sectional view, similar to FIG. 3, showing anembodiment in which a laminated magentic core is used; and

FIG. 7 is a cross-sectional view similar to FIG. 3 showing an embodimentin which a magnetic core is rolled on the casing.

DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is an antennafor use in a receiver for electromagnetic waves, which antenna comprisesa magnetic core in the form ofa thin layer superposed on the cylindricalportion of a casing of the receiver or on a block of components of thereceiver, said layer having a thickness less than 50 microns. Theprovision of a magnetic core in the form of a layer superposed on acasing or on a block of components makes the cross-sectional area of themagnetic material of the core smaller and increases the ratio of thislength to the cross-sectional area. The magnetic core according to thisinvention is very thin, but the overall assembly has a higher mechanicalstrength than conventional antenna cores, because the casing or a blockof components themselves strengthens said magnetic core. A magnetic corein the form of a thin layer superposed on the casing or the block ofcomponents requires no special space for the antenna and miniaturizesthe receiver in accordance with this invention. Referring to FIGS. 1, 2and 3, reference character 11 designates the right cylindrical portionof a casing of a receiver. The portion 11 has a hollow interior 12. Allthe components of the receiver, for example, resistors, transformers,transistors and speakers (not shown in the FIGS.) are combined togetherinto a receiver network and are positioned in the hollow interior 12 ofthe casing portion 11.

A magnetic core 13 in the form of a thin layer having a thickness lessthan 50 microns is superposed on the casing portion 11. The magneticcore according to the invention can be prepared from any availablemagnetic material having a high magnetic permeability.

A winding 14 is wound on the magnetic core 13 by a per-se well knownmethod for making an antenna for a receiver and the winding 14 iscoupled to the receiver components positioned in the hollow interior 12.It is preferable that the core 13 and the winding 14 be covered by aplastic .film 15, such as vinyl or epoxy, in order to provide theantenna with a high resistance to moisture.

The casing has a front cover 16 and a back cover 17. These covers 16 and17 protect the components in the hollow interior 12. The controllingcomponents, such as tuning or switching components, are positionednearest to the covers 16 and 17 for easy handling.

Referring to FIGS. 4 and 5, a block 21 of components is made of variouscomponents combined together into an electrical circuit and is cast ormolded into a simple cylindrical form, such as a circular cylinder, aplate or a parallelepiped by using suitable plastics such as epoxy resinor polyester resin. The necessary lead wires 22 of the block 21 extendto the casting or molding material and are connected with othercomponents so as to form a receiver network.

The block 21 has a magnetic core 23 in the form of a thin layer having athickness less than 50 microns superposed thereon, a winding 24 wound onthe core 23, and a protection film 25 which covers the core 23 and thewinding 24, as described in connection with the embodiment of FIGS. 1-3.

Materials which can be used for said magnetic cores are iron, ironnickel alloys, various ferrites and powder cores. The magnetic core inthe form of a thin layer can be superposed on the casing 11 or on theblock 21 by using per-se well known techniques, such as adhesion ofmagnetic sheets or magnetic particles, electroless plating, vacuumdeposition or applying a magnetic paste containing magnetic powder, suchas iron powder, iron alloy powder, or ferrite powder and suitable andavailable binding material, such as epoxy, polyester and vinyl.

Metals have very low electrical resistivities. Therefore, when amagnetic sheet made of a metal such as iron or nickel alloys issuperposed on the casing 11 (or on the block 21), care should be takenthat the magnetic core 13 has at least one gap 18 to prevent anelectrically short circuited winding of the core 13, as shown in FIG. 3.In addition, it is desirable for preventing eddy currents that alaminated magnetic core composed of very thin individual layers 13a,13b, and 130, as shown in FIG. 6, and together having a thickness of 50microns be employed instead of a magnetic core in one body, such as thelayer 13 of FIG. 3 or 23 of FIG. 5. It is preferable to use a magneticcore in the form of a single thin layer 13d wrapped a plurality of timesaround the casing 11, as shown in FIG. 7. The same wrapping can beplaced on block 21 shown in FIG. 5. The magnetic core l3d has the sameeffect when it is in the form of the laminated core in FIG. 7 for theprevention of the eddy current and needs no gap, such as the gap 18shown in FIG. 3.

What is claimed is:

1. An antenna consisting essentially of a casing for a receiver havingat least a portion thereof in the shape of a cylinder, a magnetic corein the form of a thin layer consisting of high magnetic permeabilitymaterial superposed on the cylindrical portion of the casing, said layerhaving a thickness less than 50 microns and having substantially nointrinsic strength and a winding wound on said magnetic core, the casingsupplying the strength for supporting the winding and the core.

2. An antenna as claimed in claim 1 wherein said magnetic core is of amagnetic metal and has at least one gap therein extending the length ofsaid core parallel to the longitudinal axis thereof.

3. An antenna as claimed in claim 1 wherein said thin layer is a thinsheet of magnetic metal wrapped around said casing a plurality of timesthe total thickness of the layer being less than 50 microns.

4. The combination as claimed in claim 1 in which said thin layer is asingle layer of magnetic material.

5. The combination as claimed in claim 1 in which said thin layer is aplurality of thicknesses of magnetic material having a total thicknessof less than 50 mi crons.

6. In combination, a block of components for a receiver having at leasta portion thereof in the shape of a cylinder and an antenna consistingessentially of a magnetic core in the form of a thin layer consisting ofhigh magnetic permeability material superposed on the cylindricalportion of said block of components, said layer having a thickness lessthan 50 microns and having substantially no intrinsic strength, and awinding on said magnetic core.

7. The combination as claimed in claim 6 wherein said magnetic core isof a magnetic metal and has at least one gap therein extending thelength of said core parallel to the longitudinal axis thereof.

8. The combination as claimed in claim 6 wherein said thin layer is athin sheet of magnetic metal wrapped around said block of components aplurality of times, the total thickness of the layer being less than 50microns.

9. The combination as claimed in claim 6 in which said thin layer is asingle layer of magnetic material.

10. The combination as claimed in claim 6 in which said thin layer is aplurality of thicknesses of magnetic material having a total thicknessof less than 50 microns.

1. An antenna consisting essentially of a casing for a receiver havingat least a portion thereof in the shape of a cylinder, a magnetic corein the form of a thin layer consisting of high magnetic permeabilitymaterial superposed on the cylindrical portion of the casing, said layerhaving a thickness less than 50 microns and having substantially nointrinsic strength and a winding wound on said magnetic core, the casingsupplying the strength for supporting the winding and the core.
 2. Anantenna as claimed in claim 1 wherein said magnetic core is of amagnetic metal and has at least one gap therein extending the length ofsaid core parallel to the longitudinal axis thereof.
 3. An antenna asclaimed in claim 1 wherein said thin layer is a thin sheet of magneticmetal wrapped around said casing a plurality of times the totalthickness of the layer being less than 50 microns.
 4. The combination asclaimed in claim 1 in which said thin layer is a single layer ofmagnetic material.
 5. The combination as claimed in claim 1 in whichsaid thin layer is a plurality of thicknesses of magnetic materialhaving a total thickness of less than 50 microns.
 6. In combination, ablock of components for a receiver having at least a portion thereof inthe shape of a cylinder and an antenna consisTing essentially of amagnetic core in the form of a thin layer consisting of high magneticpermeability material superposed on the cylindrical portion of saidblock of components, said layer having a thickness less than 50 micronsand having substantially no intrinsic strength, and a winding on saidmagnetic core.
 7. The combination as claimed in claim 6 wherein saidmagnetic core is of a magnetic metal and has at least one gap thereinextending the length of said core parallel to the longitudinal axisthereof.
 8. The combination as claimed in claim 6 wherein said thinlayer is a thin sheet of magnetic metal wrapped around said block ofcomponents a plurality of times, the total thickness of the layer beingless than 50 microns.
 9. The combination as claimed in claim 6 in whichsaid thin layer is a single layer of magnetic material.
 10. Thecombination as claimed in claim 6 in which said thin layer is aplurality of thicknesses of magnetic material having a total thicknessof less than 50 microns.